Posts Tagged ‘19:25’

Controlling Downy Mildew and Alternaria in Cole Crops

Friday, September 9th, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Symptoms of downy mildew include purple to yellowish- brown spots on upper leaf surfaces. A grayish-white spore mass will develop and cover the underside of leaves under ideal temperatures (night temperatures of 46 – 61°F and day temperatures below 75°F. Downy mildew can kill young plants. Heavily infected leaves may drop providing entry points for bacterial infections (black rot and soft rot). Symptoms of Alternaria on infected leaves include small, expanding circular lesions with concentric rings that may have a ‘shot-hole’ appearance as lesions age. Heavily infected seedlings may result in damping-off. Control of Downy mildew and Alternaria begins with preventative fungicide applications. Use one of the following at the first sign of disease and continue every 7 to 10 days (Please refer to the pesticide table on page F21 of the 2011 DE Commercial Vegetable Production Recommendations to determine which fungicide is labeled for each specific crop.):
● Quadris (azoxystrobin, 11) at 6.0 to 15.5 fl oz 2.08SC/A, or
● chlorothalonil (M5) at 1.5 pt 6F/A or OLF, or
● Cabrio (pyraclostrobin, 11) at 12.0 to 16.0 oz 20EG/A, or
● Endura (boscalid, 7) at 6.0 to 9.0 oz 70WG/A, or
● Ridomil Gold Bravo (mefenoxam + chlorothalonil, 4 + M5) at 1.5 lb 76.5WP/A (14-day schedule),
● Manzate Pro-Stick (mancozeb, M3) at 1.6 to 2.1 lb 75DF/A, or
● Switch (cyprodinil, 9) at 11.0 to 14.0 oz 62.5WG/A (Alternaria only).

For downy mildew only, apply either:
● Actigard (acibenzolar-S-methyl, P) at 1.0 oz 50WG/A (begin applications 7-10 days after thinning and re-apply every 7 days for a total of 4 applications per season.), or
● Aliette (fosletyl Al, 33) at 3.0 to 5.0 lb 80WDG/A (on 14-day schedule).

For more information please see 2011 DE Commercial Vegetable Production Recommendations Guide.

Vegetable Crop Insects – September 9, 2011

Friday, September 9th, 2011

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

Cabbage
Continue to scout all fields for beet armyworm, fall armyworm, diamondback and cabbage looper larvae.

Lima Beans
Continue to scout all fields for lygus bugs, stinkbugs, corn earworm, soybean loopers and beet armyworm. Multiple sprays will be needed for worm control.

Peppers
Be sure to maintain a 5 to 7-day spray schedule for corn borer, corn earworm, beet armyworm and fall armyworm control. You should also watch for economic levels of aphids.

Snap Beans
All fresh market and processing snap beans will need to be sprayed from the bud stage through harvest for corn borer and corn earworm control. You should also watch for beet armyworm and soybean loopers. In addition, the highest labeled rates may be needed if population pressure is heavy in your area.

Spinach
Garden webworm, Hawaiian beet webworms and beet armyworms are active at this time and controls need to be applied when worms are small and before they have moved deep into the hearts of the plants. Controls need to be applied early when worms are small and before significant webbing occurs.

University of Delaware Lima Bean Twilight Meeting

Friday, August 19th, 2011

Thursday, September 15, 2011     4:30 p.m.
UD Carvel Research and Education Center
16483 County Seat Highway
Georgetown, DE

The University of Delaware will be hosting a lima bean twilight meeting and tour on Thursday, September 15. Featured will be preliminary research results from yield trials with UD breeding materials. Other research on lima beans at UD will be discussed including breeding and evaluation for disease resistance, weed control, disease management, insect management, inoculation trials, cropping systems, regrowth cropping, and irrigation.  Researchers will be on hand to discuss their work and present current results. There will be a wagon tour to visit late season plots.

Light refreshments will be provided.

Please RSVP by Wednesday, September 14 by calling 302-856-2585 ext. 540 or emailing adams@udel.edu